Friction-clutch for dental engin es



(No Model.)

F. F. ELLIS. EEIGTION GLUTGE EOE DENTAL ENGINES. No. 547,374.

Patented 001'.. 1,1895.

Waemm.

ANDREW BRMMM. P'NOYUUTNQWASHINBTDN, D t.

rnrns llirn nfrnNr 'risica FREDERICK F. ELLIS, OF MISSOULA, MONTANA.

SPECIFICATION forming part of Letters Patent No. 547,374, dated October 1, 1895. .Lippi-attimi niet tammy 14,1895. seria No. 534,731. or@ man.)

To all whom it may concern:

Be it known that I, FREDERICK F. ELLIS, of Missoula, in the county of Missoula and State of Montana, have invented new and useful Improvements in Dental-Engine Friction- Clutches, of which the following is a specication.

This invention relates to dental engines; and it consists in the construction, combination, and arrangement of parts, as hereinafter shown and described, and specifically pointed out in the claim.

This invention is applicable to nearly all forms of dental engines; but for the purpose of illustration I have shown it applied to the head portion of an engine in common use.

Figure l representsa side elevation with the clutch applied, and Fig. 2 is a side elevation with the clutch relaxed. Fig. 3 is a front elevation ofV the parts shown in Fig. 2. Fig. t is a sectional side elevation. Figs. 5, 6, 7, 8, and 9 are side views of the different portions of the clutch mechanism detached.

A represents the upper portion of the standard of the dental engine, in which the arm A2 is pivoted and adapted to be adjusted by the ratchetteeih at.

B is the bearing for the driving-shaft casing B2, the casing in turn forming the journals for the driving-shaft B2 in the ordinary manner, as more clearly shown in Fig. 4.

D is a cord-sheave, over which the cord driving-belt D2 runs, and is formed, as shown in Fig. et, with bevel-edged cavities b Z22 on each side and mounted to run loosely upon the sleeve or shell B4, surrounding the drivingshaft B2.

Attached to the shell B4 and shaft B3, so as to revolve with them, is a collar E', having a beveled surface h3, adapted to t the beveled cavity b of the sheave D', and outside the sheave D is another drum-like collar E2, having a beveled surface b4, adapted to fit the beveled cavity h2 of the sheave. This drum E2 is hollow and fits loosely around the shellB4 by its inner end d', and is provided with a channel d2 on the outside to receive the forked end F of a lever F2, the lever being pivoted at e to a standard or arm F2, attached to the casing B2 by a set-screw e2 or other means, as shown. The lever F2 is extended above the standard F3 and is provided with an eye g to receive a cord g2, which extends to the hand of the patient in the chair, so that the `patient can by drawing down upon the cord cause the forked lever F2 to move the drum E2 outward and thus release the sheave D. The cord g2 is preferably arranged with a loop g3 to pass upon both sides of the casing B2, so as to prevent any danger of side strains upon the lever F2.

Screwed or otherwise fastened to the sleeve BL1 is a nut E2, iittinginto the outer end of the drum E2, and between which and the end d a coiled spring E4 is supported inside the drum E2, and adapted to keep the drum E2 and sheave D pressed normally against the .fixed collar E the three parts E', D', and E2 thereby forming a double-acting frictionclutch to connect the sheave D to the shaft,

so as to revolve it by the cord belt D2 so long as the lever F2 is left undisturbed.

p These dental engines are employed to operate the grinding-murs. and other implements for operating on the teeth, and they are frequently employed to grind away sensitive parts of the teeth, and the operator not always being able to determine precisely where the sensitive points of the teeth are often causes needless pain.

The object of my invention is to attach to these engines a device completely under the control of the patient, so that he can instantly stop the burr or other implement when it strikes a sensitive part of the tooth without aiecting the operative mechanism of the niachine. This, as before stated, is readily accomplished by the act of the patient in draw ing downward upon the cord g2. The action of the shaft B3 is thus perfectly controlled by the patient in the chair entirely independent of the dentist, so that if the patient feels the burr acting too severely upon a sensitive part he can instantly stop it by pulling upon the cord g2 and without the necessity of notifying the dentist. By forming the sheave D with the two concave recesses upon both sides and with the opposing clutch members adapted to compress it from both sides the pressure is equalized and no danger exists of crowding the sheave out of place byunequal side press ure. Then again by providing for the two opposing clutch members the clutch is rendered so sensitive that a very slight pull upon IOO the oord-Will release it, while at the same time a comparatively slight pressure from the spring E4 will be suflicient to hold the clutch normally compressed and in action.

Having thus described my invention, what I claim as new is- In a dental engine, a collar fast to the driving shaft and having a beveled surface, a

' drum running loosely upon-said driving shaft and with a similar beveled surface, a cord sheave running loosely upon said shaft between said collar and drum, and with beveled cavities upon its sides corresponding to said 

